<style>
    .box {
        width: 100px;
        height: 100px;
        background-color: skyblue;
        position: relative;
    }

    .box:hover .box-qrcode {
        display: block;
    }

    .box-qrcode {
        position: absolute;
        top: 100px;
        width: 100px;
        height: 100px;
        background-color: pink;
        display: none;
    }
</style>

<div class="box">
    <div class="box-qrcode"></div>
</div>